In 2010, U.S. President Barack Obama articulated his vision for the future of American space exploration, which included an eventual manned mission to Mars. Such an endeavor would surely cost hundreds of billions of dollars -- maybe even $1 trillion. Whatever the amount, it would be an expensive undertaking. In the past, only three motivations have led societies to spend that kind of capital on ambitious, speculative projects: the celebration of a divine or royal power, the search for profit, and war. Examples of praising power at great expense include the pyramids in Egypt, the vast terra-cotta army buried along with the first emperor of China, and the Taj Mahal in India. Seeking riches in the New World, the monarchs of Iberia funded the great voyages of Christopher Columbus and Ferdinand Magellan. And military incentives spurred the building of the Great Wall of China, which helped keep the Mongols at bay, and the Manhattan Project, whose scientists conceived, designed, and built the first atomic bomb.

In 1957, the Soviet launch of the world's first artificial satellite, Sputnik 1, spooked the United States into the space race. A year later, the National Aeronautics and Space Administration (NASA) was born amid an atmosphere defined by Cold War fears. But for years to come, the Soviet Union would continue to best the United States in practically every important measure of space achievement, including the first space walk, the longest space walk, the first woman in space, the first space station, and the longest time logged in space. But by defining the Cold War contest as a race to the moon and nothing else, the United States gave itself permission to ignore the milestones it missed along the way.

that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the Earth." These were powerful words, and they galvanized the nation. But a more revealing passage came earlier in the speech, when Kennedy reflected on the challenge presented by the Soviets' space program: "If we are to win the battle that is now going on around the world between freedom and tyranny, the dramatic achievements in space which occurred in recent weeks should have made clear to us all, as did the Sputnik in 1957, the impact of this adventure on the minds of men everywhere, who are attempting to make a determination of which road they should take."

Kennedy's speech was not simply a call for advancement or achievement; it was a battle cry against communism. He might have simply said, "Let's go to the moon: what a marvelous place to explore!" But no one would have written the check. And at some point, somebody has got to write the check.

If the United States commits to the goal of reaching Mars, it will almost certainly do so in reaction to the progress of other nations -- as was the case with NASA, the Apollo program, and the project that became the International Space Station. For the past decade, I have joked with colleagues that the United States would land astronauts on Mars in a year or two if only the Chinese would leak a memo that revealed plans to build military bases there.

The joke does not seem quite so funny anymore. Last December, China released an official strategy paper describing an ambitious five-year plan to advance its space capabilities. According to the paper, China intends to "launch space laboratories, manned spaceship and space freighters; make breakthroughs in and master space station key technologies, including astronauts' medium-term stay, regenerative life support and propellant refueling; conduct space applications to a certain extent and make technological preparations for the construction of space stations." A front-page headline in The New York Times captured the underlying message: "Space Plan From China Broadens Challenge to U.S."

When it comes to its space programs, China is not in the habit of proffering grand but empty visions. Far from it: the country has an excellent track record of matching promises with achievements. During a 2002 visit to China as part of my service on a White House commission, I listened to Chinese officials speak of putting a man into space in the near future. Perhaps I was afflicted by a case of American hubris, but it was easy to think that "near future" meant decades. Yet 18 months later, in the fall of 2003, Yang Liwei became the first Chinese taikonaut, executing 14 orbits of Earth. Five years after that, Zhai Zhigang took the first Chinese space walk. Meanwhile, in January 2007, when China wanted to dispose of a nonfunctioning weather satellite, the People's Liberation Army conducted the country's first surface-to-orbit "kinetic kill," destroying the satellite with a high-speed missile -- the first such action by any country since the 1980s. With each such achievement, China moves one step closer to becoming an autonomous space power, reaching the level of (and perhaps even outdistancing) the European Union, Russia, and the United States, in terms of its commitment and resources.

China's latest space proclamations could conceivably produce another "Sputnik moment" for the United States, spurring the country into action after a relatively fallow period in its space efforts. But in addition to the country's morbid fiscal state, a new obstacle might stand in the way of a reaction as fervent and productive as that in Kennedy's era: the partisanship that now clouds space exploration.

THE POLITICS OF SPACE

For decades, space exploration stood above party politics. Support for NASA was not bipartisan; it was nonpartisan. Public support for NASA, although it has waxed and waned, has generally not been correlated with the categories that typically divide Americans: liberal versus conservative, Democratic versus Republican, impoverished versus wealthy, urban versus rural. This political neutrality has been reflected even in NASA's locations. As of 2010, the congressional districts that house NASA's ten main sites were represented in the House by six Republicans and four Democrats. A similar balance existed in the Senate delegations from the eight states where those sites are located: eight Republicans and eight Democrats.

But beginning in 2004, NASA's immunity from partisanship began to fade. Following the fatal loss of the Columbia space shuttle orbiter in 2003, in which seven crew members died, experts, media commentators, and lawmakers began to push for a new vision for NASA. Less than a year later, President George W. Bush endorsed that goal with a set of policies known as the Vision for Space Exploration. The plan called for the completion of the International Space Station and the retirement of NASA's workhorse, the space shuttle, by the end of the decade. The money saved by ending the shuttle program would be used to create a new launch architecture that could take Americans to destinations farther than low-Earth orbit.

In February 2004, I was appointed by Bush to a nine-member commission whose mandate was to chart an affordable and sustainable course for implementing the new policy. The plan ultimately received bipartisan support in Congress. But during the debate over its merits, party allegiances began to distort and even blind people's ideas about space. Some Democrats were quick to criticize the plan on the grounds that the nation could not afford it, even though the commission was explicitly charged with keeping costs in check. Others complained about the plan's lack of details, although supportive documents were freely available from the White House and from NASA. A number of liberal critics questioned the advisability of spending on space when the cost of fighting two wars was already draining the Treasury and the federal government was sidelining other important programs in favor of tax cuts. They apparently failed to remember that in 1969 the United States went to the moon while fighting two wars -- one cold, one hot -- during the most turbulent decade in American history since the Civil War. A typical response came from former Vermont Governor Howard Dean, who was then contending for the Democratic presidential nomination: "I happen to think space exploration is terrific. Where is the tax increase to pay for it? It is not worth bankrupting the country." Writing in The New Yorker, Hendrik Hertzberg criticized Bush's "lack of seriousness about his interplanetary venture" and derided the plan's "Wal-Mart price tag." Criticisms such as these revealed a partisan bias I had not previously encountered in two decades of exposure to space policy.

Since Obama entered office, Republicans have taken to politicizing space exploration with no less verve. In a speech at the Kennedy Space Center on April 15, 2010, Obama put forward a new space policy, which, among other things, reaffirmed Bush's plan to retire the space shuttle. He sketched a hopeful vision for the future, built around the goal of reaching multiple destinations beyond low-Earth orbit, including asteroids. Obama even went one step further than Bush, suggesting that since the United States has already been to the moon, why return at all? With an advanced launch vehicle, he said, NASA could bypass the moon altogether and head straight for Mars by the mid-2030s.

Rather than celebrating Obama's ambitions, scores of protesters lined the causeways surrounding the Kennedy Space Center that day, wielding placards that pleaded with the president not to "destroy NASA." The conservative columnist Charles Krauthammer scoffed at Obama's "abdication" of the United States' leading role in space, labeling the plan "a call to retreat." The Republican governor of Texas, Rick Perry, accused Obama of "leaving American astronauts with no alternative but to hitchhike into space." Taken at face value, such reactions to Obama's plan could have reflected honest differences of opinion. But their partisan nature was revealed by their target: after all, it was not Obama but Bush who had originally called for the end of the shuttle program.

Ultimately, the fight over Obama's plan became all about jobs. The plan left a gap of uncertain length between the phasing out of the shuttle and new launches beyond low-Earth orbit, meaning that for some period of time, there would be no need for shuttle workers, especially the contractors who work with NASA in support of its launch operations. Since the shuttle is a major part of NASA, and since NASA's industrial partners are spread far and wide across the country, the unemployment ripples would be felt far beyond Florida'sSpace Coast. In his April 2010 speech, the president did promise to fund retraining programs for workers whose jobs would be eliminated. He also noted that his plan would erase fewer jobs than Bush's Vision for Space Exploration, although he spun the difference by saying, "Despite some reports to the contrary, my plan will add more than 2,500 jobs along the Space Coast in the next two years, compared to the plan under the previous administration." A mathematically equivalent but blunter version of that statement would have been, "Bush's plan would have destroyed 10,000 jobs; my plan will destroy only 7,500."

This emphasis on jobs led the public debate into a rhetorical cul-de-sac, since few politicians can afford to defend any federal agency, much less NASA, as a massive government jobs program. So instead of dwelling on his plan's impact on employment, Obama has focused on space travel's historic impact on technology and innovation. In a rousing speech to the National Academy of Sciences in 2009 to alert scientists of the coming benefits from the American Recovery and Reinvestment Act, the president noted that the Apollo program "produced technologies that have improved kidney dialysis and water purification systems; sensors to test for hazardous gases; energy-saving building materials; and fire-resistant fabrics used by firefighters and soldiers. And more broadly, the enormous investment of that era -- in science and technology, in education and research funding -- produced a great outpouring of curiosity and creativity, the benefits of which have been incalculable." He could have added much more to that list of revolutionary spinoff technologies, including digital imaging, implantable pacemakers, collision-avoidance systems on aircraft, precision LASIK eye surgery, and global positioning satellites.

These constitute perfectly reasonable arguments in support of spending on space. Still, there was something disingenuous about Obama's rhetoric. The economic stimulus legislation proposed doubling the budgets of the National Science Foundation, the Department of Energy's Office of Science, and the National Institute of Standards and Technology. But although Obama heaped praise on the legacy of space research, all that NASA got from the stimulus act was a directive on how to allocate $1 billion of its existing budget -- no extra funding at all. Given that space exploration formed the rhetorical soul of the president's speech, that absence of additional dollars defied rational, political, and even emotional analysis.

In his second State of the Union address, delivered in January 2011, Obama once again cited the space race as a catalyst for scientific and technological innovation. He then noted the hefty investments that other countries are now making in their technological future and the fact that the U.S. educational system is falling behind, declaring these disturbing imbalances to be this generation's Sputnik moment. He laid out four goals: to have a million electric vehicles on the road and to deploy the next generation of high-speed wireless Internet service to 98 percent of all Americans by 2015 and to derive 80 percent of U.S. electricity from clean energy and to provide 80 percent of Americans with access to high-speed rail by 2035.

Those are all laudable goals. But to think of that list as the future fruits of a contemporary Sputnik moment is dispiriting to proponents of space exploration. It reveals a change of vision over the decades, from dreams of tomorrow to dreams of technologies that should already exist.

There is also a deeper flaw in Obama's plan. In a democracy, a president who articulates a goal with a date of completion far beyond the end of his term cannot offer a guarantee of ever reaching that goal. Kennedy knew full well what he was doing in 1961 when he set out to land a man on the moon "before this decade is out." Had he lived and been elected to a second term, he would have been president through January 19, 1969. And had the 1967 Apollo 1 launch-pad fire that killed three astronauts not occurred, the Apollo program would not have been delayed and the United States would certainly have reached the moon under Kennedy's watch. Now, imagine if in 1961, Kennedy had instead called for achieving the goal "by sometime in the 1980s." With a mission statement like that, it is not clear whether American astronauts would have ever left Earth. But that is essentially what Obama has done by calling for a mission to Mars by the mid-2030s. When a president promises something beyond his years in office, he is fundamentally unaccountable. It is not his budget that must finish the job. Another president inherits the problem, and it becomes a ball too easily dropped, a plan too easily abandoned, a dream too readily deferred. So although the rhetoric of Obama's space speech was stirring and visionary, the politics of his speech were, empirically, a disaster. The only thing guaranteed to happen on his watch is the interruption of the United States' access to space.

THE LESSONS OF HUBBLE

The partisanship surrounding space exploration and the retrenching of U.S. space policy are part of a more general trend: the decline of science in the United States. As its interest in science wanes, the country loses ground to the rest of the industrialized world in every measure of technological proficiency. For example, in recent decades, the rate of U.S. submissions to peer-reviewed science journals has dropped or barely held steady, while the rates of submissions from Brazil, China, Japan, and western Europe have risen sharply. Data on graduate-level education tell a similar story. According to the latest available annual census by the National Science Foundation, nearly one-third of the graduate students in science and engineering fields in the United States and more than half of the postdoctoral researchers in those fields are foreign nationals studying or working in the country on temporary visas. Moreover, those numbers partly cloak the fact that in some of the nation's best engineering departments, almost all the students are foreign nationals.

Until recently, most of those students came to the United States, earned their degrees, and gladly stayed for employment in the U.S. high-tech work force. Now, however, department chairs are anecdotally reporting that foreign nationals in their graduate programs are choosing to return home more frequently, owing to a combination of widespread anti-immigrant sentiment and increased professional opportunities in China, India, and eastern Europe -- the places whose citizens are the most highly represented in advanced academic science and engineering programs in the United States. This is not a brain drain, because the United States never laid claim to these students in the first place, but a kind of brain regression. Thus, what is bad for America is good for the world. In the next phase of this shift, the United States should expect to begin losing the talent that trains the talent, which would be a disaster. Ever since the Industrial Revolution, investments in science and technology have proved to be reliable engines of economic growth. If homegrown interest in those fields is not regenerated soon, the comfortable lifestyle to which Americans have become accustomed will draw to a rapid close.

Nevertheless, there are still reasons to be hopeful. One of the most popular museums in the world, with attendance levels rivaling those of the Metropolitan Museum of Art, the Uffizi, and the Louvre, is the National Air and Space Museum, in Washington, D.C. Some of its visitors are, of course, foreign tourists. But Americans' continued interest in exhibits such as the Wright brothers' original 1903 airplane and the Apollo 11 moon capsule reflects the way that an enduring emotional investment in space exploration has become part of American culture.

Or consider the fate of the Hubble Space Telescope. Hubble's scientific legacy is unimpeachable. Its data have been used in more published research papers than data from any other single scientific instrument, in any discipline. Among the highlights of Hubble's achievements is the way it helped settle a decades-old debate about the age of the known universe (now agreed to be about 14 billion years). Yet in 2004, when NASA announced plans to cancel an upcoming mission to service Hubble, owing to a lack of funds and the risks inherent in using an aging shuttle fleet, the loudest voices of dissent were not those of scientists but rather those of everyday Americans.

Hubble is the first and only space telescope to observe the universe using primarily visible light. Its crisp, vibrant, and detailed images of the cosmos make it a kind of supreme version of human eyes in space. No matter what Hubble reveals -- planets, dense star fields, colorful interstellar nebulae, deadly black holes, gracefully colliding galaxies -- each image opens up a private vista of the cosmos. Hubble came of age in the 1990s, during the exponential growth in access to the Internet. Soon, Hubble images, each more magnificent than the last, became screen savers and desktop wallpaper on the computers of people who had never before found reason to celebrate, however quietly, Earth's place in the universe. Those gorgeous images made Americans feel that they were participants in cosmic discovery. And so, when the source of those images was threatened, there followed a torrent of letters to the editor, online comments, and phone calls to Congress, all urging NASA to restore Hubble's funding. I do not know of any previous point in the history of science when the public took ownership of a scientific instrument. The largely unorganized campaign to save Hubble succeeded: the decision was reversed, and the funding was restored.

Hubble offers another lesson about the value of space exploration. When it was launched in 1990, a flaw in the design of its optics system produced hopelessly blurry images, much to NASA's dismay. Three years later, corrective optics were installed. But during the intervening time, astrophysicists at Baltimore'sSpace Telescope Science Institute, the research headquarters for Hubble, continued collecting the murky data and also worked to design advanced image-processing software to help identify and isolate stars in the telescope's otherwise crowded, unfocused images. Meanwhile, in collaboration with Hubble scientists, medical researchers at the Lombardi Comprehensive Cancer Center at Georgetown University Medical Center recognized that the challenge faced by the astrophysicists was similar to that faced by doctors in their visual search for tumors in mammograms. With the help of funding from the National Science Foundation, the Lombardi researchers adapted the techniques that the Hubble scientists were using to analyze the telescope's blurry images and applied them to mammography, leading to significant advances in the early detection of breast cancer. Countless women are alive today because of efforts to fix a design flaw in the Hubble Space Telescope.

PLANNING FOR TOMORROW

One cannot script those kinds of outcomes, yet similar serendipitous scenarios occur continually. The cross-pollination of disciplines almost always stimulates innovation. Clearly defined, goal-oriented support for specific outcomes in specific fields may yield evolutionary advances, but cross-pollination involving a diversity of sciences much more readily encourages revolutionary discoveries. And nothing spurs cross-pollination like space exploration, which draws from the ranks of astrophysicists, biologists, chemists, engineers, planetary geologists, and subspecialists in those fields. Without healthy federal support for the space program, ambitions calcify, and the economy that once thrived on a culture of innovation retreats from the world stage.

Other good reasons abound for supporting space science. Humans should search Mars and find out why liquid water no longer runs on its surface; something bad happened there, and it would be important to identify any signs of something similar happening on Earth. We should visit an asteroid and learn how to deflect it -- after all, if we discover one heading toward Earth, it would be rather embarrassing if big-brained, opposable-thumbed humans were to meet the same fate as the pea-brained dinosaurs. We should drill through the miles of ice on Jupiter's frozen moon Europa and explore the liquid ocean below for living organisms. We should visit Pluto and other icy bodies in the outer solar system, because they hold clues to the origin of our planet. And we should probe Venus' thick atmosphere to understand why the greenhouse effect has gone awry there, raising surface temperatures to 500 degrees Celsius. No part of the solar system should be beyond our reach, and no part of the universe should hide from our telescopes.

What the Bush plan and the Obama plan have in common, apart from having exposed partisan divides, is an absence of funding to bring their visions closer to the present, let alone an unspecified future. In the current economic and political climate, it might be difficult to imagine much support for a renewed commitment to space exploration -- even in the face of a direct challenge from China. Many will ask, "Why are we spending billion of dollars up there in space when we have pressing problems down here on Earth?" That question should be replaced by a more illuminating one: "As a fraction of one of my tax dollars today, what is the total cost of all U.S. spaceborne telescopes and planetary probes, the rovers on Mars, the International Space Station, the recently terminated space shuttle, telescopes yet to orbit, and missions yet to fly?" The answer is one-half of one penny. During the storied Apollo era, peak NASA spending (in 1965-66) amounted to a bit more than four cents on the tax dollar. If the United States restored funding for NASA to even a quarter of that level -- a penny on the tax dollar -- the country could reclaim its preeminence in a field that shaped its twentieth-century ascendancy.

Even in troubled economic times, the United States is a sufficiently wealthy nation to embrace an investment in its own future in a way that would drive the economy, the country's collective ambitions, and, above all, the dreams of coming generations. Imagine the excitement when NASA, bolstered by a fully funded long-term plan, starts to select the first astronauts to walk on Mars. Right now, those science-savvy future explorers are in middle school. As they become celebrities whom others seek to emulate, the United States will once again witness how space ambitions can shape the destiny of nations.

(AUTHOR BIO: Neil deGrasse Tyson is Director of the Hayden Planetarium at the American Museum of Natural History. His latest book is Space Chronicles: Facing the Ultimate Frontier (Norton, 2012), from which this essay is adapted.)